Capability chart for generator-transformer units

The concept of capability chart, traditionally related to the synchronous machines, is extended to the whole generator-transformer unit, including not only the limitations due to the generator technical limits but also the characteristics of the step-up transformer and of the electrical power system the unit is connected to. The capability chart for generator-transformer units proves to be an effective tool in planning and design activities; different solutions can be compared in terms of active and reactive powers actually injected by the generating unit into the high-voltage busbar. To highlight the effectiveness of the tool numerical applications are presented with reference to a typical generating unit